A culture medium is the most direct and important environmental factor for determining growth and metabolism of cultured cells in vitro. Animal cell culture medium typically contains additives derived from animals, such as serum. However, with global fulminant epidemic of mad cow disease, use of animal derived additives, such as serum, brings transmissible spongiform encephalopathy (TSE) virus and other dangerous substances in biopharmacy industry, sharply increasing security risk for the biopharmacy industry. Drug regulators all over the world require drug makers to reduce the use of bovine derived constituents during pharmaceutical production, and relevant legislatures are increasingly opposing the use of animal derived constituents such as bovine serum in pharmaceutical field. Use of animal derived constituents in commercial production of culture medium is strictly controlled by the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA) to ensure medication safety of a patient. Meanwhile, serum and other animal derived culture medium additives contain macromolecular proteins such as growth factor, transport protein, anchoring factor and hormone, which will affect post-separation and purification of biological products such as antibody-medicine and vaccine, and eventually affect yield of the product obtained, increasing cost of production. Therefore, development and application of non-animal derived cell culture medium additives accords with current developing direction, and has become an important subject in culture of animal cells in vitro and biopharmacy fields.
Corn gluten meal can be obtained by wet-milling corn to obtain crude starch milk, separating protein from the crude starch milk to obtain gluten water, and then concentrating and desiccating the gluten water. The corn gluten meal is a major by-product during wet-milling process of corn to produce starch, which contains more than 60% of protein, and inorganic salts and a variety of vitamins. Corn active peptide is a mixture of small molecular peptides obtained from the corn gluten meal as a raw material by pretreatment, enzymatic hydrolysis, multi-stage separation and purification, concentration and desiccation and other processes. Corn active peptide is a sophisticated product in the field of bio-processing and conversion utilization of natural corn protein resources. The corn active peptide is derived from plant protein, and thus the problem that animal derived constituent such as serum is potentially polluted by virus microorganism can be avoided; quality thereof is consistent between batches, which is advantageous to improve producing stability of cell products; the corn active peptide contains no macromolecular protein, which is beneficial to downstream separation and purification of the cell products.
The corn active peptide is rich in nutrient substances, and easy to be polluted by bacteria microorganism during processing and storing, thus producing a large amount of bacterial endotoxin. It will change cell morphology, damage cell membrane structures and induce cell apoptosis, etc., when used as a cell culturing additive, which is disadvantageous to growth of the cell cultured in vitro. In addition, different processes have great influence on composition of the obtained corn active peptide product, while constituents of animal serum are complex wherein many constituents are unknown up to now, therefore, it cannot be determined that whether existence or absence of one or some constituents will adversely affect cell growth, which accordingly brings difficulties to application of the corn active peptide as a serum-free culture medium additive.